1. Field of the Invention
The invention relates to a valvular ring, a nd in particular to a valvular ring designated on a cup rinse for preventing a chemical liquid leakage from causing peripheral instruments damages.
2. Description of the Related Art
It is well known that photolithography is one of the most important steps in the semiconductor process. Any regions related to the structure of semiconductor devices, such as subsequently pattered and doped regions, are all defined by photolithography. Thus, the complexity of the semiconductor process depends on the times of photolithography performed and the numbers of mask used.
Although the photolithography is complicated, the principle thereof is quite simple. To perform the photolithography, a photo-sensitive material is first formed on a wafer. A parallel light coming from a light source passes through a glass-based mask and irradiates the photo-sensitive material. At the same time, a pattern on the mask is projected onto the photo-sensitive material. A selective photo-sensitive reaction is performed to accomplish a pattern transfer. In general, the photo-sensitive material is called a photoresist.
Currently, a non-defect photoresist with a better uniformity and a higher adhesion is formed on a wafer by spin coating. Referring to FIG. 1, there is shown a spinner used for spin coating. An appropriate vacuum is provided inside the axis of a spinner 10 to suck a wafer 12 thereon. When the spinner 10 rotates the wafer 12, a photoresist liquid 14 is sprinkled on the rotated wafer 12 and then removed towards the circumference thereof owing to a centrifugal force, thereby forming an uniform photoresist layer 16.
Next, Referring to FIG. 2, the relationship between the spinner of FIG. 1 and a cup rinse is shown. In FIG. 2, the spinner shown with dotted lines rotates with a high speed. A fixed container 20 is used to prevent sprinkling part of a photoresist liquid 21 onto the ground. However, after a long-term operation, the interior surface of the fixed container 20 is almost covered by part of the photoresist liquid 21. To remove the stuck photoresist liquid 21 covering the interior surface of the fixed container 20, a cup rinse 22 is installed under the spinner. Furthermore, an inlet tube 24 is inserted through a ring 32 on the bottom of the cup rinse 22 to allow a chemical liquid, such as an OK-82 solution, to flow into the cup rinse 22. Then, the chemical liquid is sprayed to the fixed container 20 thereby to clean the stuck photoresist liquid. At the same time, the sprayed and used chemical liquid flows into a base 26 along the wall of the fixed container 20. Subsequently, the chemical liquid collected in the base 26 is discharged out via an outlet tube 28. A precision motor (not shown) is located in a region 30 surrounded by the base 26.
FIGS. 3A-3C are a side view, a top view and a cross-sectional view of the ring 32 shown in FIG. 2. It can be obviously seen from FIGS. 3A-3B that the center of the ring 32 is hollow. Therefore, the chemical liquid can easily flow onto the ground when the cup rinse 22 is dismounted.
FIG. 4 shows that a chemical liquid flows out onto the ground when the dismounted cup rinse is removed. During maintenance, the cup rinse 22 must be first dismounted. At this time, the chemical liquid can flow out through the hollow ring 32, even though the inlet tub 24 is pulled out of the ring 32. To prevent the above-stated problem, the chemical liquid must completely flow to the base 26 and then discharged out via the outlet tube 28 before dismounting the cup rinse 22. However, part of the chemical liquid can be sprinkled on the motor (not shown) located in the center region 30. This causes a serious damage on the motor, since the chemical liquid used for removing a stuck photoresist liquid has a strong corrosion. For example, if part of the chemical liquid is sprinkled on the axis of the motor, it causes the motor totally broken down.